verb
diddle
DID-uhl/ˈdɪdl/
to cheat someone or manipulate something dishonestly
The seller diddles the customer by secretly keeping one coin.

Etymology
The source treats diddle as a suggestive sound around which several more or less unrelated meanings gathered. The cheating sense is recorded as slang, without an established root explaining it.
More examples
- They diddled us out of half our deposit.
- Someone has diddled the figures to hide the missing money.
- That mechanic diddles customers by charging for repairs he never makes.
Forms
diddle · diddles · diddled · diddling
swindler noun — someone who cheats others out of money